BUILT TO LAST

Nothing raises the hackles of ecological campaigners more than the felling of the world's rain forests. We are told that they must be revered as places untouched by man, home to the most diverse range of organisms on Earth. But has eco-politics clouded the scientific reality? Here Fred Pearce debunks the myth of `virgin' rain forest and argues that they have endured extensive clearing. And overleaf Matthew Brace meets the scientists who believe it is the grasslands which are the greatest sources of bi...

Once we had jungles. They were dangerous impenetrable places, full of wild animals; places to be felled and tamed. Now we have renamed them rain forests. They are still impenetrable, still full of wild animals. But they are also places to be cherished and protected, not razed to the ground. They are the "lungs of the planet", home, it is said, to half of the Earth's species and the last great bastions of nature in an overpopulated world.

The old myth of the untamed frontier awaiting the hand of man has been replaced by another, encapsulating new feelings about the grandeur of the natural world. Many scientists foster this new myth. For Edward Wilson of Harvard University, one of the world's leading biologists, they are "timeless, immutable ... the crucible of evolution". British forest expert and fellow of Green College, Oxford, Norman Myers calls them "the finest celebration of nature that has ever graced the face of the planet."

But the modern perception of the rain forest as virgin territory, unchanged and primeval, is itself under assault from a new generation of scientists who see them as temporary, unstable and as much a product of human activity as of Mother Nature.

Take Deborah and David Clark. As husband and wife directors of the remote La Selva forest research station in Costa Rica, they emerged three years ago from the forest to report their discoveries - not a new species of beetle or a tree bark that yields a cure for cancer (another potent rain forest myth), but of charcoal, corn pollen and farm tools buried in the soil in the heart of the forest. The whole area, they reported, had been used for slash-and-burn agriculture for most of the past 2,000 years.

The high forest of La Selva, apparently the epitome of a pristine rain forest, turned out to be no virgin. Far from being thousands of years old, most of it is a recent regrowth, a garden gone wild after being abandoned by farmers, perhaps less than 500 years ago, when Europeans invaded Central America. "There is no such thing as virginity out there," says Deborah Clark.

Michael Williams, geography professor at the University of Oxford agrees. "Almost everywhere you go in Latin America, Asia and Africa, you will find charcoal buried in the soil. People have in one way or another cut and burned almost every place in the tropics."

"Fire is a fantastically good marker of human influence," says Steve Pyne, a fire researcher from the Arizona State University. "And everywhere there is evidence of fires. You find a sudden eruption of charcoal in the soil, usually along with other evidence, such as pottery. It is especially clear in places where we know that farmers arrived late, such as Iceland, Madagascar and southern Greenland."

Take the Amazon, the world's largest rain forest region, crowning glory of the rain forest myth. Says veteran Amazon researcher William Denevan, until recently professor of geography at the University of Wisconsin: "We are finding charcoal in the soil all across the Amazon. Some could perhaps be from natural fires, even in such damp forests. But all the evidence of fires comes from the last 10,000 years, since humans arrived there."

In the past decade, archaeologists have found increasing evidence that humans in the Amazon were doing much more than burning a clearing in the forest, planting some crops and then moving on. Great civilisations rose and fell here. Anna Roosevelt of the Field Museum of Natural History in Chicago has found massive earthworks on Marajo, an island in the mouth of the River Amazon that is twice the size of Wales. They are, she says, evidence of a lost civilisation dating back perhaps 6,000 years. She concludes that, at the same time as the Greek empire flourished in Europe, the Amazon basin was dotted with large towns, canals, roads and irrigation and drainage networks.

Further west in Bolivia, Denevan and later anthropological researchers such as Clark Erickson of the University of Pennsylvania have found tens of thousands of hectares of forests and wetlands covered by fields raised up on ridges to prevent waterlogging. The earthworks involved in such creations were "comparable in scale to the pyramids," says Erickson. "They completely altered the landscape. But today it is empty and abandoned land, save for a regrowth of forest. Some people want to conserve the forests. That is fine, but there is no way they are pristine. Every feature of the land is man-made.

Similar raised field systems have turned up across South America. Peter Stahl of the State University, New York has excavated in Ecuador. "I've looked at the fragmentary remains of the teeth of rodents in archaeological sites that were until recently covered in forests. There are two sorts of rodents: those that live in trees and those that live in grasslands. The finds show that over the past 2,000 years, an area that we once thought of as pristine forest has in fact been deforested several times."

In Guatemala, you don't need to examine rodents' teeth to get at the past. The pyramids of the Mayan civilisations, now submerged in lush rain forest, are the highly visible remains of a culture that levelled large areas of rain forest from some 3,000 years ago until the 16th century. Likewise in Panama, six millennia of intensive farming ended with wars between native Indians and Spanish conquistadores, and dense forest invading the cleared grasslands. American science author Stephen Budiansky points out in his book, Nature's Keepers: "Areas that in the early 16th century could be ridden through with ease on horseback are now accessible only by river."

Forest farmers didn't merely destroy, they often embellished and improved. American anthropologist Darrell Posey, who spent a decade living with the Kayapo Indians in the Brazilian Amazon, says within the forests their ancestors planted many "forest islands" containing fruit trees. Likewise in North America, says Williams, supposedly virgin forests turn out to have been planted with wild peaches and sassafras by past generations of Indians.

Knowledge of these past works is often largely lost. Roosevelt's research colleague, William Balee of Tulane University, New Orleans, says native civilisations all over Latin America have been in wholesale retreat since the arrival of Europeans on the continent, with cities abandoned, and farmers reverting to hunting and gathering. The Guaja tribe, for instance, who live in the Maranhao state in Brazil, grew maize 250 years ago. "Something happened. It could have been an epidemic from the Old World - and it drove some groups extinct and the others were so reduced that they could not maintain their agriculture. Eventually they lost their domesticated plants." The primitive nature of Stone Age tribes still "discovered" from time to time in the Brazilian forests, is due to the arrival of Europeans. Likewise, much of the "virgin" rain forest of the Amazon may be regrowth following the exterminations by conquering Europeans.

Denevan believes that the greater part of the Amazon forest could have been cleared by humans in past millennia. There is evidence that only a few isolated areas survived through the last ice age, which ended 10,000 years ago. The conventional view is that this deforestation was due to a drier climate at that time. But, Denevan says, "you can reduce rainfall by 50 per cent and still get forests in most of the Amazon, so perhaps humans played a role."

Much the same news comes from the tropical rain forests of southeast Asia. There are, says Phil Stott, a geographer at the School of Oriental and African Studies in the University of London, "very few pristine forests in Asia". The classic southeast Asian forests of the Malay peninsula was a savannah grassland little more than 10,000 years ago. And the forest that grew since then has probably all been changed to some extent by human activities. In Cambodia, the remains of the city of Angkor Wat, for instance, are only a small part of a major civilisation that grew three or four rice crops a year on land that is now covered in forest.

In Africa, Victor Gornitz of the Lamont-Doherty Earth Observatory at Columbia University in New York, studied the history of its natural vegetation and concluded that "very little virgin tropical forest remains today in West Africa". Much of the apparently pristine high forest "is mature secondary forest, which was once cleared for agriculture and later abandoned."

Africa has its equivalents of Angkor Wat and the Mayan pyramids. In the forests of southern Nigeria, British archaeologist Patrick Darling, of Bournemouth University, has mapped what he calls "the largest single archaeological phenomenon on this planet". Some 16,000 kilometres of earth ramparts are all that remains of the ancient Benin civilisation that flourished in the area between 500 and 1,000 years ago. The ramparts, now overgrown, appear to form boundaries of land cleared from the forest. They are five times longer than the Great Wall of China.

James Fairhead and Melissa Leach of the Institute of Development Studies at the University of Sussex examined the forests of Guinea in their book, Misreading the African Landscape. "People have been reading the landscape backwards," says Leach. "Wherever there are some trees, a presumption is made that there was, and indeed there ought to be, continuous forest cover." But while environmentalists claim that the West African forests have been disappearing fast in the past 40 years, there is often more forest cover today than a generation ago," she says. Villagers planting and tending woodlands for their own purposes are custodians rather than destroyers. And despite recent population growth, the actual population levels are often lower than before the arrival of European slave traders on the shores of the continent, when great empires such as the Benin and Ashanti thrived.

The impact of myths about virgin rain forests can be pernicious, especially for the people who live in those forests. The myth of the virgin forest gives rise to the myth of the demon farmer. Traditional slash-and-burn farmers become defiled as abusers of the forest. They are excluded from national parks and forest reserves arbitrarily declared on their land. They are cajoled and forced from the forests.

Stott criticises the whole notion of pristine forests as an ecological concept. "It starts from the old ideas of ecologists about nature creating a natural equilibrium." Ecologists believed that, left to its own devices, nature evolved towards forests, and that forests themselves evolved into a stable community with great biological diversity, a climax forest. "Ecologists in other environments, such as grasslands, got away a long time ago from the idea of natural equilibrium," says Stott. "But it is only now happening with forests," In fact, he says, even without human influence, forests are in a constant state of change, under stress from changing climate and forest fires, insects and storms. Indeed these stresses may themselves create the exceptional biodiversity of tropical rain forests. "There is really no such thing as a primeval ancient forest, even in nature."

As if that weren't enough to distress environmentalists, they may now have to cope with the idea that many apparently pristine tropical forests are a response to the arrival of Europeans. The evidence is especially strong in the Americas, where European arms and disease decimated large populations of Amerindians in South and Central America, shattering their civilisations and forcing the survivors to flee. Result: empty rain forests.

But the same may hold for North America, where 19th-century writers such as Henry Longfellow popularised the idea that Europeans had arrived on a continent covered by uninterrupted "forest primeval". The wisdom remains to this day that, as American environmental historian Gordon Whitney puts it, the forests of pre-Columbian North America were "a world undefiled by man's hands, a world that directly reflected the hands of its Creator."

Rubbish, insists Budiansky. The forests that the settlers found were not only largely human in their creation, a product of the activities of the native Amerindians, but were also completely unlike the dense forest of 19th-century imaginings. "One of the great ironies in the myth of the forest primeval is that the dense, thick woods that later settlers did indeed encounter, and arduously cleared, were not the remnants of the `forest primeval' at all. They were the recent, tangled second growth that had sprung up on once-cleared Indian lands only after the Indians tehmselves had been cleared or evicted." He quotes from an early Massachusetts settler, William Wood, who in 1639 had noted that "in some places where the Indians died of the Plague some 14 years ago, is much underwood because it hath not been burned."

What later writers took for the forest primeval "was nothing more than an abandoned ranch." They had been blinded by "the cult of the wild", the yearning to find and touch something unsullied by humankind. Not unlike our own desire to see rain forests as, in Wilson's words, "timeless, immutable ... the crucible of evolution." !

YOU CAN'T SEE THE WOOD FOR THE TREES

Even in Europe, claims are made for the existence of ancient, pristine wildwood, such as the remnants of the Caledonian forest in Scotland, the "old growth" pine forests of Scandinavia and the oak forests of central Europe. But "our great wild woods passed away in prehistory and has left neither written record nor legend", says Oliver Rackham, a geographer at the University of Cambridge and author of the classic work, The History of the Countryside. Virtually the whole of Britain was denuded of its wild woods between 4,000 BC and 2,000 BC. Britain then probably contained far fewer trees than it does now, with forested areas of today, such as Breckland in East Anglia, destroyed.

The great forests of Germany, Poland and Russia are the stuff of much myth, including the fairy-tales of the Brothers Grimm. The forests were symbols of dark and evil. But how wild were they? "There is plenty of evidence that they were quite well populated for a long time," says Rackham. "They came to be seen as savage in the Middle Ages. One suspects the idea was put about by people with an interest in conquering them." Steve Pyne, in a book to be published next year, An Environmental History of Europe Through Fire, shows that Scandinavia is no different. Sweden, though two- thirds covered in forest, contains no pristine wildwood - not even in the empty near-tundra of Lapland.

Archaeologists, says Rackham, have unwittingly conspired to reinforce the myths of forest as wild land. "It is difficult to find evidence of past civilisations or human activity in forests because the evidence gets covered up by vegetation," he says. "Knowing this, archaeologists avoid going there. The temptation is to assume lack of evidence means there's nothing to be found."

Even before the invention of farming, humans were altering landscapes, including forests, (using fire to hunt, exterminating many great mammals). "By Columbus' time," says Rackham, "there were not many forests, other than on uninhabited islands, that had never been altered by human activities."